* refact: Changes required for gorm v2
* refact: Add db.DB wrapper and refact all test fixtures to use it
Stop leaking the gorm abstraction within our unit tests.
* refact: Migrate direct calls to pq to pgx driver
The refactor will remove the remaining direct dependencies on
the pq driver which has been deprecated in favor of the pgx
driver.
It includes the addition of common.SqlOpen which is a wrapper around
sql.Open, which is needed to deal with the driver name changing from
"postgres" to "pgx" but in our code base the dialect and driver are
synonyms.
The docker package and its StartDbInDocker function should only be used
by the `boundary dev` command now. So moving it into an internal package
of `base` will prevent it from being use for tests accidentally, while
still allowing it to be used for `boundary dev`.